Silver and silver compounds have long been known for their antimicrobial properties. See Disinfection, Sterilization, and Preservation, p. 375 (Seymour Block 3rd edition, Lea & Febiger, Philadelphia, 1983) (chapter 18 authored by N. Grier, entitled "Silver and Its Compounds").
Silver and silver compounds have been incorporated into a number of wound dressing articles. In particular, various wound dressing substrates have been coated with metallic silver. UK Patent Application GB No. 2 134 791 A describes a surgical dressing prepared by vapor coating or sputter coating Sphagnum moss with metallic silver or a silver/carbon composite. European Patent Application No. 0 099 758 describes a composite wound dressing comprising a semipermeable membrane, a permeable layer and a biodegradable layer wherein the permeable layer may be fabric coated, impregnated or plated with silver. U.S. Pat. No. 2,934,066 describes a metallized bandaging material prepared by vapor coating metallic silver onto a fiber fleece. U.S. Pat. No. 4,419,091 describes an electrode for ion therapy comprising a substrate of polymer fibers wherein each of the fibers is coated with silver.
Other means of providing silver or a silver salt at the site of wound have also been used in wound dressings. U.S. Pat. No. 4,340,043 describes an adhesive-coated liquid-impervious moisture-vapor permeable thin polymer sheet which has an antibacterial silver salt incorporated into the adhesive. U.S. Pat. No. 3,830,908 describes a synthetic plastic sheet powder-coated with an organic silver salt allantoin complexx. U.S. Pat. No. 3,800,792 describes a laminated collagen foam film dressing with finely divided metallic silver impregnated in the collagen layer. U.S. Pat. No. 4,446,124 describes a wound dressing comprising silver sulfadiazine incorporated in animal tissue, e.g. pigskin. Genetic Laboratories, Inc. is currently marketing a product called E-Z DERM.TM. temporary skin substitute for the treatment of burns. This product is a biosynthetic wound dressing having silver nitrate incorporated therein.
While the prior art described above has solved various problems encountered in the art of antimicrobial wound dressing, they do not possess the advantages of the wound dressings of this invention.